Method of processing coffee



Oct. 22, 1935. P. T. CLARY METHOD OF PROCESSING COFFEE Filed April 24,1933 INVENTOR Among the objects I have in view are the following.

The reduction in the loss in weight which in the present practice isexperienced in the roast ing of the cofiee beans.

The improvement in the quality and flavor of the coffee.

The indefinite retention in the coiiee after grinding of the improvedflavor.

The impregnating oi the coffee with suitable flavor-preserving orimproving substances, such for instance as salt.

Other objects will appear from the following description.

For the sake of clearness in describing the present practice andcomparing therewith my improved method I have illustrated in theaccompanying drawing a well known type of cofieeroasting machine, Fig. 1being a longitudinal section thereof taken along the line I--l in Fig.2.

Fig. 2 is a cross sectional view taken along the line 2-2 in Fig. l.

In the present practice the coffee is loaded into the horizontallydisposed drum I whose perimetral wall is perforated and which drum isrotatably mounted as on the rollers 2 within the roaster casing 3. Thedrum is rotated on a horizontal axis as by means of a suitably drivenshaft 5 extending into the casing and carrying apinion 5 which mesheswith the ring gear 6 on the drum. The shaft i may also carry a pair offriction rollers i which assist in supporting and rotating the drum. Theinterior of the drum is provided with baiiies 8 and 9 by means of whichthe blanket or layer of coffee which is carried by the inner wallsurface of the drum is caused to shift longitudinally of the drum as thelatter is revolved.

The heat for roasting the mice is supplied by a gasburner l0 whichextends through an opening in the casing 3 into one end of the drum l. Astationary inverted V-shaped shield ii extends into the end of the drumabove the course of the flame from the burner. I2 is a perforated waterpipe which extends into the drum within the shield II.

In thep'resent practice the drum I is rotated continuously during theprocessing of the coffee, the roasting being accomplished by means ofthe flame from burner 10, and the water being cut oil from the pipe l2during the roasting process. When the roasting operation has beencompleted the gas is cut oil from burner l0 and water is admittedthrough the perforated pipe l2, the water being sprayed over therevolving blanket of cofiee. During this process of adding moisture tothe to escape freely through the stack It. When the is eneration ofsteam slackens ed the water is cut ofl from the pipe i2 and the door itis opened, and the coiiee beans are-discharged from the roaster.

In the present practice the shrinkage in weight of the coffee resultingfrom the roasting process 10 is relatively high, in the case of Santoscotfee running from 14% to 16%. Further, shrinkage can not besuccessfully prevented by the-addition of more water, because in suchcase the coffee beans become water-logged and lose their crispness andthe flavor and quality of the ground coffee is seriously impaired.

In my improved process the operation is the same during the applicationof heat for roasting purposes but when the moistin'e or water is sup- 20plied to the coffee, after the burner has been shut ed, the damper i3 isclosed so that the steam which is generated can not escape up the stackid but is held in the casing and in the drumexcept for the relativelysmall percentage which escapes through the openings in the casing.

The damper however is not entirely closed at first but is left partiallyopen, thus stopping the further roasting of the beans. Then the damperis fully closed to hold the steam in contact with $0 the beans.

As the result of this confinement of the steam within the casing of theroaster I find that I am able to add a much larger quantity of water toa given quantity of coffee beans and I have in some cases doubled theamount of water used, as will appear from the test table hereinaftercontained.

As the result of my improved method I am able to cut down the shrinkagein weight of the coffee very materially as will appear from the testtable, such reduction running in said tests up to as much as over 4%.

I also found, after a long period of careful experiment, that althoughthe shrinkage is re- I duced and more water is used, the cofiee beansare as crisp as after treatment by the present process. Again the cofieetreated by my present process when compared by expert cofiee tasterswith cofiee of the same grade and character treated sired steam may besupplied through the pipe I? instead of water either hot or cold.

The following is a table of tests made by the Pittsburgh TestingLaboratory in which various lots of Santos No. 4 coffee were processedby the present accepted practice and also by my improved method and thetable shows the points of improvement which I have accomplished. TestsNos. 1 and 2 were made with two bags of coffee each or about 264 pounds.Tests Nos. 3 and 4 were made with four bags each, or about 527 pounds.Tests Nos. 5 and 6 were also made with four bags each.

keep it from having a bitter taste. Thus in restaurants where the coffeeis made in large quantities, as in coffee urns, and is allowed to standfor a considerable time the made coffee tends to become bitter andsometimes salt is added to the liquid coffee to prevent itsdeterioration in taste.

With my improved process it is feasible and advantageous to add the saltto the water which is introduced into the coffee after the roasting hasbeen accomplished and before the coffee is discharged from the roaster.

If the salt be added in the present process it Roast Number 1 2 3 4 5 6Method Old method New method Old method New method Old method New methodCoiieeused No. 4 Santos No. 4 Santos No. 4 Santos No. 4 Santos No. 4Santos N0. 4 Santos Duration of roast in minutes 28 14% 30 26 Wateradded 5 gal. 10 gal. Steaming interval in 1:20 1:40 1:40 3:15 Greenweight, lbs 263 264. 5 526. 527. 0 526. 0 526. 0 Roasted weight, lbs 224232. 442. 5 465. 5 442. 5 464. 5 Shr nkage, lbs s9 32 a 83.5 61. 5 s3. 5c1. 5 Shrinkage, percent 14. 8 12. 1 15. 9 l1. 7 l5. 9 1i. 7 Analysis ofroasted cofl Moisture 1. 54 3. 62 1. 48 4. 76 1. 80 3. 68

Oils (ether extract) i5. 62 12. 60 11. 20 9. 40 13. 60 12. 70

Cold water extract 25. 45 23. 9 22. 32 21. 62 29. 05 29. 10

Acidity of cold water extract 6. 45 5. 81 6. 09 5. 92

Acidity of ether extract--... 04 04 Ash 3. 79 3. 77 4. 17 4.19 4. 214.09

It Will be noted that the shrinkage in the case will be deposited on theouter surface of the coffee of Roast No. 1 amounted to 14.8%, while inRoast No. 2 it amounted to 12.1%. Again in Roast No. 3 it amounted to15.9%, while in Roast No. 4 it amounted to 11.7%. In Roast No. 5 itamounted to 15.9% and in Roast No. 6 it amounted to 11.7%. Roasts Nos.1, 3 and 5 were made by the old practice, while Roasts Nos. 2, 4 and 6were made by my improved process.

Thus the average shinkage by the old process was 15.53%, while theaverage shrinkage by the new process was 11.83%, giving an averagereduction by the new process of 3.7%.

A number of interesting phenomena are evident from these tests. Thus itwill be noted that the moisture content of the product is greatlyincreased when my improved method is used, and thus there is a greatsaving in weight. This is also shown by comparing the green weight andthe roasted weight as shown by the above tests. It is also noted thatthe oils (ether extract) are less in amount in the product of myimproved process than they are in the product of the old process. As thedeterioration in coffee is often caused as the result of rancidity incoffee the reduction of the oils in the product is of advantage.

An examination of the foregoing tests will show many other advantages toone skilled in the art of coffee roasting.

Frequently it is desired to add substances to coffee to improve itsflavor and more often to beans and will be dislodged when-the coffee ishandled and ground, but I have found that with my improved process thesalt may be successfully introduced by being added to the water or steamduring the processing and that it will become impregnated throughout thecoflee beans and thus will be retained by the cofiee when ground.

By the use of my improved process I am able to obtain superior grades ofprepared coffee from the same quality and character of raw coflee beans.

I claim:-

1'. The method of processing coffee beans which comprises the steps ofroasting the beans, then applying moisture to the heated beans andconfining the resultant steam in contact with the beans to properlyimpregnate the latter.

2. The method of processing cofiee beans which comprises the steps ofroasting the coffee beans, then spraying water on the heated beans andconfining the resultant steam in contact with the beans to properlyimpregnate the latter.

3. The method of processing coffee beans which comprises the steps offirst roasting the beans, then spraying the heated beans with watercontaining in solution a suitable flavor-influencing substance such assalt, and then confining the resultant steam in contact with the beansto impregnate the beans with such substance.

PATRICK T. CLARY.

